Magnetic recording elements are usually in either tape, disc or card form and are comprised of a nonmagnetic carrier (substrate) having at least one surface coated with a layer of magnetic pigment and lubricant dispersed by means of a dispersing agent in an organic polymeric binder. Such recording elements can be used for recording audio, video or digital information.
The problem underlying the present invention relates to the function of the lubricant. In particular, lubricants reduce the frictional force between the recording/playback head of the magnetic recording apparatus and the magnetic tape moving past the head. The lubricants are operative at the surface of the magnetic coating and they must be capable of reaching said surface. This implies that the lubricants are not quite compatible with the binder and, as a result of this, have a tendency to diffuse to the surface. This also implies that in the case of variations in temperature and degree of humidity, too much or too little lubricant may move to the surface. When too much lubricant reaches the surface, the magnetic tape becomes sticky and lubricant is deposited on the recording/playback head. On the other hand, in the case of too little lubricant, irregular tape travel is likely to be obtained.